In recent years, an amount of information processing that is needed is increasing along with the improvement of information processing technologies and the development of internet environments. Associated with such tendency, data center business which installs and operates equipment such as servers, communication devices, fixed-line phones and IP (Internet Protocol) telephones that are used for the internet is being paid attention.
A lot of electronic devices such as a computer are installed in a server room of such a data center. As a method to install electronic devices in a server room, using a rack-mounting system is the mainstream. A rack-mounting system is a method standardized by JIS (Japanese Industrial Standards) and EIA (Electronic Industries Alliance), in which flat type electronic devices are installed in a rack in a stacked manner.
In order to reserve a space in a server room sufficiently, it is desired to mount electronic devices into a rack as much as possible. Therefore, it is needed for electronic devices that the heights of them are made to be short respectively. Meanwhile, the height of an electronic device such as a 1 U (Unit) server and a blade server which are generally called a rack-mount type server is about 40 millimeters. In order to cool heat exhausted by such rack-mount type servers, it is necessary to simultaneously cool a plurality of stacked heat sources having different heights.
An underfloor air-conditioning system is a general cooling system for a data center. To cool servers in a data center efficiently, in an underfloor air-conditioning system, a building in which servers are laid is made to have double floors, and cool wind from air-conditioning equipment is supplied to server racks from an under floor through a floor grill, which is provided on a floor surface and is made of a metal plate having a plurality of opened holes. This underfloor air-conditioning system can supply a cool wind to a server rack efficiently because a warm air of a server and a cool wind from air-conditioning equipment can be separated through double floors.
A cooling air volume required for a server rack varies greatly by a load of a server. Therefore, there is disclosed in patent document 1 a structure in which a supplied amount of a cold air that is blown out to the front of a rack is controlled according to a heat generation amount of the rack to reduce motive power for cold air supply and to prevent occurrence of a hot spot.
That is, an average operating rate for each rack is obtained from an operating rate of each server taken in from a control server, the maximum air volume of a rack is multiplied by the average heat generation amount of the rack obtained from that value, and, by that, a signal of a required air volume is generated. Based on this required air volume signal, the number of rotations of a floor fan of each rack is being controlled.
Furthermore, there is provided a temperature correction arithmetic processing part to correct a required air volume signal when an inlet detection temperature of an upper part thermometer provided in a position corresponding to the inlet of a server exceeds an inlet temperature that has been set.
Thus, by obtaining an air volume required for a server from an average operating rate of a server rack and a server inlet air temperature of the uppermost stage of the server rack, a required air volume and a cool wind temperature of air-conditioning equipment are adjusted according to a server operating rate which changes every moment and a cool wind having the most suitable temperature and an air volume is supplied to each server.